There are already known processes of the type wherein a given number of truing tools are moved along the generatrices of the surface of the head of rails, the tools being so positioned with respect to the rail section to true the surface by eliminating irregularities either initially present or resulting from wear due to stresses caused by the rolling material.
Those irregularities are mainly shaped as undulatory deformations having an amplitude and a wavelength which vary in accordance with the cause involved as well as their location around the outline of the head of the rails.
It therefore becomes necessary, at every use, to adjust the metal-removing capability of the truing tools in proportion to the variations of those deformations.
For this purpose, the value of at least one parameter acting on the metal-removing ability of a single or a group of truing tools, is brought under the control of a set control value in order to adjust the cutting depth of said tools to the actual condition of the surface. Thus, the bearing pressure, the cut speed, the inclination angle and the displacement speed of the truing along the rails are effectively controlled.
The setting of the control value assigned to those various parameters is manually performed pursuant to a personal estimate made by operators, and the quality of the grinding which is carried out according to that process still depends, on a large part, on the operator's experience and skill.
When quantitative evaluations are to be observed, a mere qualitative estimate from the operator does not suffice and it becomes necessary to control the carried-out truing by measuring their irregularities remaining on the head surface of the trued rails. Those measurements are presently gathered by means of independently controlled vehicles which supply, as they progress along the railway, a graphic record in the form of a diagram showing the running evolution of the amplitude and the wavelength of the undulatory deformations. The resulting diagtam is thereafter examined to determine the values of the residual deformations in order to establish the necessary quantitative comparison with predetermined values of acceptable deformations. Finally, based on the results of such comparison, the operators decide on carrying out a second truing operation of the same segment of rail and on the setting of new control values for the second cut.
The end result of such a process is satisfying, but it is lengthy, it requires numerous manipulations and still depends heavily on the experience of the operator.